<?php

declare(strict_types=1);
/**
 * Copyright (c) The Magic , Distributed under the software license
 */

namespace Aws;

use Aws\Api\Parser\Exception\ParserException;
use Aws\Exception\AwsException;
use Exception;
use GuzzleHttp\Promise;
use InvalidArgumentException;
use Psr\Http\Message\RequestInterface;
use Psr\Http\Message\ResponseInterface;
use RuntimeException;

/**
 * Converts an HTTP handler into a Command HTTP handler.
 *
 * HTTP handlers have the following signature:
 *     function(RequestInterface $request, array $options) : PromiseInterface
 *
 * The promise returned form an HTTP handler must resolve to a PSR-7 response
 * object when fulfilled or an error array when rejected. The error array
 * can contain the following data:
 *
 * - exception: (required, Exception) Exception that was encountered.
 * - response: (ResponseInterface) PSR-7 response that was received (if a
 *   response) was received.
 * - connection_error: (bool) True if the error is the result of failing to
 *   connect.
 */
class WrappedHttpHandler
{
    private $httpHandler;

    private $parser;

    private $errorParser;

    private $exceptionClass;

    private $collectStats;

    /**
     * @param callable $httpHandler function that accepts a request and array
     *                              of request options and returns a promise
     *                              that fulfills with a response or rejects
     *                              with an error array
     * @param callable $parser function that accepts a response object
     *                         and returns an AWS result object
     * @param callable $errorParser function that parses a response object
     *                              into AWS error data
     * @param string $exceptionClass exception class to throw
     * @param bool $collectStats whether to collect HTTP transfer
     *                           information
     */
    public function __construct(
        callable $httpHandler,
        callable $parser,
        callable $errorParser,
        $exceptionClass = AwsException::class,
        $collectStats = false
    ) {
        $this->httpHandler = $httpHandler;
        $this->parser = $parser;
        $this->errorParser = $errorParser;
        $this->exceptionClass = $exceptionClass;
        $this->collectStats = $collectStats;
    }

    /**
     * Calls the simpler HTTP specific handler and wraps the returned promise
     * with AWS specific values (e.g., a result object or AWS exception).
     *
     * @param CommandInterface $command command being executed
     * @param RequestInterface $request request to send
     *
     * @return Promise\PromiseInterface
     */
    public function __invoke(
        CommandInterface $command,
        RequestInterface $request
    ) {
        $fn = $this->httpHandler;
        $options = $command['@http'] ?: [];
        $stats = [];
        if ($this->collectStats || ! empty($options['collect_stats'])) {
            $options['http_stats_receiver'] = static function (
                array $transferStats
            ) use (&$stats) {
                $stats = $transferStats;
            };
        } elseif (isset($options['http_stats_receiver'])) {
            throw new InvalidArgumentException('Providing a custom HTTP stats'
                . ' receiver to Aws\WrappedHttpHandler is not supported.');
        }

        return Promise\Create::promiseFor($fn($request, $options))
            ->then(
                function (
                    ResponseInterface $res
                ) use ($command, $request, &$stats) {
                    return $this->parseResponse($command, $request, $res, $stats);
                },
                function ($err) use ($request, $command, &$stats) {
                    if (is_array($err)) {
                        $err = $this->parseError(
                            $err,
                            $request,
                            $command,
                            $stats
                        );
                    }
                    return new Promise\RejectedPromise($err);
                }
            );
    }

    /**
     * @return ResultInterface
     */
    private function parseResponse(
        CommandInterface $command,
        RequestInterface $request,
        ResponseInterface $response,
        array $stats
    ) {
        $parser = $this->parser;
        $status = $response->getStatusCode();
        $result = $status < 300
            ? $parser($command, $response)
            : new Result();

        $metadata = [
            'statusCode' => $status,
            'effectiveUri' => (string) $request->getUri(),
            'headers' => [],
            'transferStats' => [],
        ];
        if (! empty($stats)) {
            $metadata['transferStats']['http'] = [$stats];
        }

        // Bring headers into the metadata array.
        foreach ($response->getHeaders() as $name => $values) {
            $metadata['headers'][strtolower($name)] = $values[0];
        }

        $result['@metadata'] = $metadata;

        return $result;
    }

    /**
     * Parses a rejection into an AWS error.
     *
     * @param array $err rejection error array
     * @param RequestInterface $request request that was sent
     * @param CommandInterface $command command being sent
     * @param array $stats Transfer statistics
     *
     * @return Exception
     */
    private function parseError(
        array $err,
        RequestInterface $request,
        CommandInterface $command,
        array $stats
    ) {
        if (! isset($err['exception'])) {
            throw new RuntimeException('The HTTP handler was rejected without an "exception" key value pair.');
        }

        $serviceError = 'AWS HTTP error: ' . $err['exception']->getMessage();

        if (! isset($err['response'])) {
            $parts = ['response' => null];
        } else {
            try {
                $parts = call_user_func(
                    $this->errorParser,
                    $err['response'],
                    $command
                );
                $serviceError .= " {$parts['code']} ({$parts['type']}): "
                    . "{$parts['message']} - " . $err['response']->getBody();
            } catch (ParserException $e) {
                $parts = [];
                // Reset stream position to ensure we can read the full response body
                $body = $err['response']->getBody();
                if ($body->isSeekable()) {
                    $body->rewind();
                }
                $responseBody = (string) $body;
                $serviceError .= ' Unable to parse error information from '
                    . "response - {$e->getMessage()}. Raw response: " . $responseBody;
            }

            $parts['response'] = $err['response'];
        }

        $parts['exception'] = $err['exception'];
        $parts['request'] = $request;
        $parts['connection_error'] = ! empty($err['connection_error']);
        $parts['transfer_stats'] = $stats;

        return new $this->exceptionClass(
            sprintf(
                'Error executing "%s" on "%s"; %s',
                $command->getName(),
                $request->getUri(),
                $serviceError
            ),
            $command,
            $parts,
            $err['exception']
        );
    }
}
